Investigation of a Base-Isolator System’s Effects on the Seismic Behavior of a Historical Structure

The earthquake performance of structures with seismic isolation is much better than that of fixed-base structures, and the application of seismic insulation ensures both structural integrity and the protection of the items present in the structures. The base-isolation system is used to extend the fundamental period of vibration of the structure and to obtain higher value from base-isolated structures relative to the fixed-base structure. Historical masonry mosques could be strengthened using a base-isolation technique. In this study, a historical masonry mosque was organized and modelled using SAP2000 software. Nonlinear Time History analyses were carried out for the historical masonry structure, firstly for the fixed-base mosque and secondly for the base-isolated mosque with lead rubber bearing (LRB). The use of a base-isolator system caused an increase in the historical mosque’s period, reducing the displacements, acceleration, and force applied on the mosque and the resulting structural deformation; the results of the analysis indicate a significant improvement in the seismic behavior. The modelling results show that such historical masonry buildings (especially those with high and delicate minarets) can be vulnerable to major earthquakes, and it may be useful to examine strengthening strategies for these buildings.

Influence at Mass of the Base Isolation System in Affecting the Higher Modes of Vibration

Base Isolation is a technology of mitigating the effects due to earthquakes with the aspect of dissipating the seismic waves away from the superstructure, by isolating the superstructure from the ground.This concept is widely essential to be implemented in structures(buildings) irrespective of many factors. There are several materials which could be implemented as base isolator, however the need in reduction of the number of the isolators is essential dueto various factors which a developing country finds difficult to implement. In this paper, a three-storey unsymmetrical building to be considered for the study is isolated by varying the mass of the foundation beam, (Transfer beam) thereby reducing the number of isolators in the building.Furthermore,the mode shapes and frequencies of the structure without base isolation and with base isolation considering mass of the base isolation system as a key factor were analysed and compared and hence the variation in the mass of the isolation system has a promising effect in altering the higher modes of vibration. The analysis is prolonged using another methd using UBC-1997 provisions and compared. In both the methods, the influence of the mass of the isolation system has a remarkable effect in altering the higher modes of vibration.

Base Shear Struktur Beton Bertulang Yang Menggunakan Base Isolator Akibat Beban Gempa Dengan Menggunakan Etabs

The sudden release of energy within earth creates seismic waves on earth’s surface that is earthquake. This research was carried out using a base isolator type of HDR with Certification Number MVBR-0516 (XO.3R) to reduce base shear, displacement and internal forces acting on the structure. This study uses time history analysis method with some earthquake loads in the form of acceleration acceleration. The objectives of the study were to determine the base shear of a reinforced concrete structure building using a base isolator and without using a base insulator. The results of this study indicate the use of base insulators reduces base shear by about 20% -67% and 14% -70.5% for earthquakes in the x direction to the east and west. Meanwhile, in the y direction earthquake, it was around 43% -70% and 43% -62% to the south and north

Performance of elevated water tank staging with base isolation under blast loading

In this present study aims to evaluate the performance of base isolation device under different intensity blast induced ground excitations for an elevated water tank staging. In this study mainly focused to improve the performance of the base isolator and minimize the damage of the structure. To know the performance of base isolator two models are considered one is fixed base model and another one is supported with base isolator model for both non-linear time history analysis is carried out with the help of SAP 2000 software subjected to four different underground blast intensities. From the analysis, it is observed that by using base isolator supported model structural responsive parameters such as base shear, top storey accelerations are efficiently reduced when compared to the fixed base structure. Hence it is proved that adopting base isolation technique we considerably reduce the damage of the structure subjected to underground blast vibrations.

New Mexico City International Airport - Control Tower

<p>The New International Airport in Mexico City is being built on some of poorest ground conditions that exist in Mexico City, or indeed anywhere. The ground is extremely soft, rapidly sinking and exposed to a major and unique seismic site hazard. This paper discusses the performance–based engineering design of the 90 m tall Control Tower. The tower is base isolated to significantly reduce the seismic accelerations which would approach 1.0 g with a fixed-base design. The airport site is predicted to settle by 5 m over the 75-year design life due to regional subsidence. A practical, efficient and elegant solution was developed using a shallow pile-enhanced and compensated raft, and a transfer truss which supports the lightweight braced steel tower on seismic base isolator bearings, allowing the building to be founded on the soft soils while accommodating regional subsidence by moving down with it. The design accommodated seismic joint movements of 1.4 m.</p>

Pengaruh Penggunaan Base Isolation High Damping Rubber Bearing Pada Struktur Beton Bertulang

Salah satu cara yang dapat dilakukan adalah menggunakan peredam beban gempa dengan sistem isolasi dasar (base isolation system). Penggunaan base isolation system pada bangunan dapat mengisolasi perambatan getaran akibat gempa dari tanah ke struktur atas bangunan menggunakan komponen berbahan karet. Tujuan penelitian ini adalah untuk menganalisis pengaruh penggunaan sistem isolasi dasar berupa High Damping Rubber Bearing pada periode dan gaya geser dasar struktur beton bertulang. Objek penelitian adalah bangunan hotel 15 lantai dengan ketinggian 62,9 m. Penelitian diawali dengan pemodelan struktur menggunakan aplikasi ETABS v2016 sehingga didapatkan periode dan gaya geser dasar struktur fixbase. Tahap selanjutnya memberikan gaya pada model struktur dengan isolasi dasar High Dumper Rubber Bearing sehingga didapatkan periode dan gaya geser dasar struktur dengan base isolator. Hasil analisis pada struktur fixbase didapatkan periode sebesar 4,212 detik, dengan gaya geser dasar didapatkan sebesar 1470,725 ton. Sedangkan hasil analisis pada struktur dengan base isolator didapatkan periode sebesar 5,500 detik, dengan gaya geser dasar didapatkan sebesar 1286,071 ton. Maka dapat disimpulkan bahwa pada struktur dengan base isolator terjadi peningkatan periode sebesar 30,58 %, sedangkan gaya geser dasar terjadi penurunan 12,56 %.